Abbreviation for "Beyond Economic Repair". Generally used to describe damage, usually crash damage to a vehicle (especially an airframe) which is so badly mangled that to fix it would cost more than replacement; the best option is to salvage any reuseable parts and junk the rest.

"How's your bike ?"
"Shit, both wheels buckled and the frame bent. It's B.E.R., I'm going to get a new one on the insurance."